Multiple loop control



June 24, 1947. AYERS 2,422,651

MULTIPLE LOOP CONTROL Filed Dec. 51, 1943 2 Sheets-Sheet l I I L I l l 0 I 3 1 '8 Q;

INVENTOR M40 MED/H4595, g-@205 June 24, 1947. AYERS MULTIPLE LOOP CONTROL Filed Dec. 51, 1943 2 Sheets-Sheet 2 Qm NM. wm r Wm. i||||\|l| llllm r wi QN NmN $w- %N mww Q mwwmv wmfi wN QN F m G M g YWQ 9 m W mme m r 4 WWW Patented June 24, 1947 2,422,5l

UNITED, STATES PATENT OFFICE MULTIPLE LOOP CONTROL Maurice D. Aura-Pittsburgh, Pa., assignor to Carnegie-Illinois Steel Corporation, a corporation of New Jersey Application December 31, 1943, Serial No. 516,583

16 Claims. (Cl. 2712.3)

' 1 z This invention relates to a multiple loop com the looper pit 2 to the pit 4 where a second loop trol for a continuous processing line or the like. I2 is formed. A rolll4 located on the outgoing In continuous strip processing lines, such as elecside ofthe pit 4 supports the strip as it leaves trotinning, pickling, and the like, one coil of the pit. The strip is then pul e 'throu h the strip must be welded or otherwise fastened to a 5 processing q p t indicated schematically succeeding coil and during this welding opera at l6 by means of the drive bridle rolls l8. The tion the tail end of the leading strip must be rolls 8, l0 and i8 are rotated by means of convenstationary. In order to keep the strip moving tional shunt field D. C. motors 28, 22 and 24 rethrough the processing equipment during welding spectively. While the rolls 6, l0 and I 8 are shown it is necessary to provide an accumulation of 10 as pinch rolls, magnetic feed r0115 y be strip prior to the entry oi. the strip into the stituted therefor if desired. For example, in high processing equipment. In coating operations, if Speed lines andling wide light gage, annealed the speed through the coating equipment is and soft coated products, pinch rolls should be slowed down to a great extent, a non-uniform avoided since they act as screws, eventually shiftcoating and otherwise defective strip is obtained. mg the material on the rolls until the edge 0 1 Various means have been used to accumulate and are damaged aga n t th ho sings of the strip. pinch roll stands or against side guides which are In the patent to Rendel, No. 2,306,750, strip is p i o the entry side of the feed rollsaccumulated in a looper pit, the strip being percated in pit 2 are four photoelectric cells or other mitted to rest on the bottom of the pitwith folds light responsive devices and 3 Sim of the strip accumulating one upon another, lar photoelectric cells 34, 36, 38 and 40 are located While this permits a long length of strip t be in pit 4. The pits are provided with light sources accumulated, the strip becomes scratched and 54 a 55, which p e thus is unsuitable for many purposes. the light necessary to energize the respective In the patent to Wells, No. 2,238,667, a double 25 photo t c c one light being located op loop is formed in the strip, but there is no site each photoelectric cell. The photoelectric means provided for keeping the length of the cells in the loop pits cause relays to function tov two loops uniform. There is danger of the strip increase decrease t Speed Of the mOtOIS resting on the bottom of the it d/ of t 20, 22, and 24 by varying the field resistances. majority oi. strip accumulating in one loop while 30 The operation of the loop control is as follows:

the other loop practically disappears. The strip X is threaded through the rolls 6 and It is an object of my invention to provide a ill, the processing equipment It and the drive multiple loop control which overcomes the disadrolls i8; the loops 8 and i2 being close to the tops vantages of the loops discussed above. of the pits 2 and 4. The starting switch 58 is then Another object is to provide a loop control operated manually to admit control current to which will slow down and stop the feeding means the relay 80, closingthe main line contactors 62. in case the loop becomes dangerously short. The circuit from the control lines 84, 85 to the A still further object is to provide a multiple coil 60 is completed throu lines 68, closed loop control having means for maintaining the contact Ill, closed switch 58, and line 12. Closing lengths oi! the various loops approximately conof the main line contactors 62 provides power to stunt. motor 20 from the power lines 14 and 15 through These and other objects will be more apparent lines 16 and 18 having norma y closed Contacts after referring to the following specification and 80 therein. Power is provided to motors 22 and attached drawings, in which: through lines 8|, 82 and 84, 88 respectively.

Figures 1 and 1A constitute a single figure Hand'adjustments on field control rheostats 88 broken on the line X--X and shows a schematic and 90 for motors 20 and 22, respectively, are set layout of the multiple loop and the controLthereso that the motors feed the strip into the pits 2 for. and 4 slightly faster than motor 24 draws the Referring more particularly to the drawings, strip .out. When the loops interrupt the light the reference numerals 2 and 4 indicate looper beams of circuits 4a and 4b, the coils of relays pits in a continuous processing line. The strip 92 and 84 are de-energized causing their respec- X to be processed, passes between pinch rolls 8 tive contacts to open. When both of these conwhich feed the strip to the pit 2 where a loop 8 tacts are open, the operating coil of relay 96 is is formed. Between the pits 2 and 4 is a second de-energized, opening its contact which in turn pair of pinch rolls in which feed the strip from causes a motor controller 98 to start the reversible motor I of the rheostat I02. This increases the resistance in the field circuit I04, I and thereby speeds up all three motors 20, 22 and 24. Adjustable rheostats I06 and I08 in the field circuit of motors and 22, respectively, are set so that these motors feed strip into the pits faster than the motor 24 draws it out. The speed of motor 24 may be adjusted by changing the setting of the variable resistance I I0. With motors 20 and 22 operating at a faster rate than motor 24, loops 8 and I2 continue to lower until they interrupt the light beams of circuits Ia and ID. This de-energizes the coils of relays H2 and H4, respectively, causing their contacts to close and closing the circuits to the coils of relays IIS and H8, respectively, which cuts out the upper portions of the variable resistances I05 and I08, increasing the field current flowing to motors 20 and 22 and slowing them down slightly. Loops 8 and I2 continue to lower slowly until the light beams of circuits 2a and 2b are interrupted. This de-energizes the coils of relays I20 and I22, respectively, causing their contacts to close and completing the circuit to the coils of relays I24 and I26. Energization of the coils closes the contacts of relays I24 and I25, this cutting out more of the resistance of adjustable resistances I08 and I08 and further increases the field current of motors 20 and 22 which lowers their respective speeds. The two portions of the resistance I05 and I08 which are cut out as described above are adjustable and are set by hand to obtain the correct relative speeds of the motors 20 and 22. These adjustments are such that the loop normally remains below the light beam of circuits 2a and 2b. In case the loops 8 and I2 should go lower due to slight maladjustment of the resistances or other factors they will interrupt light circuits 3a and 3b, de-energizing the coils of relays I28 and I30 respectively, causing their contacts to close, which closes the contacts of relays I32 and I34 to short circuit resistances 88 and 90. This increases the field current of motors 20 and 22 respectively, further slowing them down. Any suitable amplifier I35 may be used in the photoelectric circuits to amplify the current generated by the photoelectric tubes. It will be understood that the control for the loop 8 will operate independently of the control for loop I2, but that control of one loop must necessarily change the length of the other loop, which in turn will bring the control for the second loop into operation. When the loops are decreasing in length, their respective controls will operate in the reverse manner, thus speeding up the respective motors. The relative speeds of the motors are so set that during normal operation of the line, loops 8 and I2 will seek the position shown in full lines and will maintain this position in the absence of unusual circumstances.

In case either loop 8 or I2 rises so high in the pits that circuits 4a or 42) are completed, the coil of relays 92 or 94 will be energized, closing its contact. Closing of contact 92 completes the circuit to the coil of relay 96 through lines 65, I36 and I2. Closing of the contact of relay 94 completes the circuit to the coil of relay 96 through lines 68, I35 and I38. Energization of the coil of relay 96 closes its contacts and completes the circuit to motor controller 98, which decreases the resistance of motor operated rheostat I02. This in turn increases the field current to motors 20, 22 and 24, slowing them down so that the processing line can be stopped readily without excessive drifting. Located near the top of pits 2 and 4 are limit switches I40 and I42 arranged in series. Each of the switches has an arm I43 extending into the respective loops and adapted to be actuated thereby to open the switch when the loop rises close to the top of the pit. Opening of either switch I40 or I42 breaks the circuit to the stop relay 10, which in turn opens the circuit to the main line relay 50, opening the switches 62 and stopping all motors. Suitable brakes may be used to stop the motor quickly when the power is; shut off. These slow down and stop circuits prevent possible damage to the equipment or breaking of the strip in case the other controls do not operate properly, or in case of delays during welding.

When it is necessary to stop the pinch rolls 8 to weld a succeeding coil of strip to the tail end of strip X the operator closes switch I44. This completes the circuit to the coil of relay 96 through line I45, the coil of relay I48, line I50, the coil I52, lines I38, 86. Closing of the contacts of relay 95 completes the circuit to motor controller 98, which decreases the resistance of motor operated rheostat I02 to slow down motors 22 and 24. Energization of coil I52 opens contacts and stops motor 20. Energization of the coil of relay I48 opens its contacts and places the variable resistance I I0 in the field circuit of motor 24, this causing the motor 24 to operate at twice the speed of motor 22. For example, the normal speed of the line may be 600 feet per minute. If the amount of available loop in the pits is feet and the time interval required for making a weld or othewise fastening the strips together is 15 seconds, the motor 24 must be slowed down to a speed of 360 feet per minute. Motor 20 is stopped and in order for both loops 8 and I2 to be used simultaneously, motor 22 must drive the rolls I0 at half the speed or feet per minute. The proper motor speeds under any particular conditions are obtained by adjusting the various resistances shown to obtain the required field current of the motors once set for a particular condition, these resistances are not changed. For normal starting of the line, the starting switch 58 is used. In case limit switches I40 or I42 have stopped the line, it is necessary to use the starting switch I54.

If desired, any number of loops may be provided with similar operating mechanism. If more than two loops are used, the speeds of the various motors will be so adjusted during welding that the loops will be used simultaneously. In all cases the speed of motor 22 will be equal to the speed of motor 24 divided by the number of loops and the speed of each motor will be equal to the speed of the next preceding motor plus the speed of motor 22.

While one embodiment of the invention has been shown and described, it will be more apparent that other adaptations and modifications may be made without departing from the scope of the following claims.

I claim:

' 1. Strip handling apparatus comprising means for forming a multiple loop in said strip, individual means for feeding strip to each of said loops at variable speeds, means for feeding the strip from the last of said loops, means responsive to the position of each of said loops for varying the speed of their respective feeding means, means for stopping the feeding of the strip to the first loop and means responsive to said last named means for causing the feeding means to the succeeding loops to operate at a lower rate of speed "than the next succeeding feeding means.

2. Strip handling apparatus comprising means for forming a multiple loop in said strip, individual means for feeding strip to each of said loops at variable speeds, means for feeding the strip from the last of said loops, means responsive to the position of each of said loops for varying the speed of their respective feeding means, means for stopping the feeding of the strip to the first loop, means responsive to said last named means for causing the feeding means to the succeeding loops to operate at a lower rate of speed than the next succeeding feeding means, and means to stop said feeding means when any of said loops reaches a given height;

,3. Strip handling apparatus comprising means for forming a multiple loop in said strip, individual means for feeding strip to each of said loops at variable speeds. means for feeding the strip from the last of said loops, a light responsive device for each loop adapted to speed up the respective feeding means as the loop controlled thereby decreases in length and to slow up the feeding means as the loop increases in length, means for stopping the feeding of the strip to the first loop and means responsive to said last named means for causing the feeding means to the succeeding loops to operate at a lower rate of speed than the next succeeding feeding means.

4. Strip handlingv apparatus comprising means for forming a multiple loop in said strip, indi-' vidual means for feeding strip to each of said loops at variable speeds, means for feeding the strip from the last of said loops, a light responsive device for each loop adapted to speed up the respective feeding means as the loop controlled thereby decreases in length and to slow up the feeding means as the loop increases in length, means for stopping the feeding of the strip to the first loop, means responsive to said last named means for causing the feeding means to the succeeding loops to operate at a lower rate of speed than the next succeeding feeding means,

and means to stop said feeding means when any of said loops reaches a given height.

5. Strip handling apparatus comprising means for forming a multiple loop in said strip, a variable speed feed roll for each of said loops, means for feeding the strip from the last of said loops, a plurality of light responsive devices located at differentlevels of each loop, the lower devices being adapted to speed up their respective feed rolls as the loop controlled thereby decreases in length and to slow up the last named rolls as the loops increase in length, the highest of said devices being adapted to slow down their respective feed rolls as the loop controlled thereby decreases in length and to speed up the last named rolls as the loops increase in length,'means for stopping the feeding of the strip to the first loop and means responsive to said last named means for causing the feed rolls for the succeeding loops to operate at a lower rate of speed than the next succeeding feed roll.

6. Strip handling apparatus comprising means for forming a multiple loop in said strip, a variable speed feed roll for each of said loops, means for feeding the strip from the last of said loops, a plurality of light responsive devices located at different levels of each loop, the lower devices being adapted to speed up their respective feed rolls as the loop controlled thereby decreases in length and to slow up the last named rolls as the loops increase in length, the highest of said devices being adapted to slow down their respective \any of said loops reaches a given height.

'7. Strip handling apparatus comprising means for forming a multiple loop in said strip, a motor driven feed roll for eachloop, a motor driven roll for feeding the strip from the last of said.

loops, 9. light responsive device for each loop adapted to speed up the respective feed roll as the loop controlled thereby decreases in length and to slow up the feed roll as the loop increases in length, said first named rolls normally operating at approximately the same lineal speeds, means for stopping the feeding of the strip to the first loop and means responsive to said last named means for causing the feed rolls for the succeeding loops to operate at a lower rate of speed than the next succeeding feed roll.

8. Strip handling apparatus comprising means for forming a multiple loop in said strip, a motor driven feed roll for each loop, a motor driven roll for feeding the strip from the last of said loops, a light responsive device for each loop adapted to speed up the respective feed roll as the loop controlled thereby decreases in length and to slow up the feed roll as the loop increases in length, said first named rolls normally operating at approximately the same lineal speeds, means for stopping the feeding of the strip to the first loop,

means responsiveto said last named means for causing the feed rolls for the succeeding loops to operate at a lower rate of speed than the next succeeding feeding means, and means to stop said feed rolls when any of said loops reaches a given height.

9. Strip handling apparatus comprising means for forming a multiple loop in said strip, a motor driven feed roll for each loop, said rolls normally operating at approximately the same lineal speeds. a motor driven roll for feeding the strip from the last of said loops, a plurality of light responsive devices located at different levels of eachloop, the lower devices being adapted to "speed up their respective feed rolls as the loop controlled thereby decreases in length and to slow up the last named rolls as the loops increase in length. the highest of said devices being adapted to slow down their respective feed rolls as the loop'controlled thereby decreases in length and to speed up the last named rolls as the loops increase in length, means for stopping the feeding of the strip to the first loop and means responsive to said last named means for causing the feed rolls for the succeeding loops to operate at a lower rate of speed than the next succeeding feed rolls.

' 10. Strip handling apparatus comprising means for forming a double loop in said strip, a motor driven roll for feeding the strip to the first of ,said loops. a second motor driven roll for feeding the strip from the first to the second loop, a third motor driven roll for feeding the strip from said second loop, said rolls normally operating at approximately the same speeds, a plurality of light responsive devices located at different levels of each loop, the lower devices being adapted to speed up their respective feed rolls as the loop controlled thereby decreases in length and to slow up the last named rolls as the loops increasein length, the highest of said devices being adapted to slow down their respective feed rolls as the loop controlled thereby decreases in length and to speed up the last named rolls as the loops increase in length, means to stop said motors when either of said loops reaches a given height, means for stopping the rotation of said first roll, and means responsive to said last named means for causing the second feed roll to operate at approximately one-half the speed of the third roll.

11. Strip handling apparatus comprising means for forming a loop in said strip, means for feeding strip to said loop at variable speeds, means for feeding strip from said loop, a plurality of light responsive devices located at diflerent levels of the loop, the lower device being adapted to speed up its feeding means as the loop decreases in length and to slow up the feeding means as the loop increases in length, the highest of said devices being adapted to slow down its feeding means as the loop decreases in length and to speed up the feeding means as the loop increases in length, means for stopping the feeding of the strip to the loop and means responsive to said last named means for slowing down the means for feeding strip from said loop.

12. Strip handling apparatus comprising means for forming a multiple loop in said strip, individual means for feeding strip to each of said loops at variable speeds, means for feeding the strip from the last of said loops, means for stopping the feeding of the strip to the first loop, and means responsive to said last named means for decreasing the rate of feed to each of the succeeding loops, the feed to each loop being decreased less than the feed to the next succeeding loop.

13. ;Strip handling apparatus comprising means for forming a multiple loop in said strip, individual means for feeding strip to each of said loops at variable speeds, means for feeding the strip from the last of said loops, means responsive to the position of each of said loops for varying the speed of their respective feeding means, means for stopping the feeding of the strip to the 8 first loop, and means responsive to said last named means for changing the rate of feed to at least one of the succeeding loops.

14. Strip handling apparatus com means for forming a multiple loop in said strip,

- individual means for feeding strip to each of said loops at variable speeds, means for feeding the strip from the last of said loops, means for stopping the feeding of the strip to the first loop, and means for decreasing the rate of feed to each of the succeeding loops after stopping feeding of the strip to the first loop, the feed to each loop being decreased less than the feed to the next succeeding loop.

15. Strip handling apparatus comprising means'for forming a multiple loop in said strip, individual means for feeding strip to each of said loops at variable speeds, means for feeding the strip from the last of said loops, means responsive to the position of each of said loops for varying the speed of their respective feeding means, means for stopping the feeding of the strip to 'the first loop, and means for changing the rate of feed to at least one of the succeeding loops after stopping feeding of the strip to the first loop.

16. Strip handling apparatus comprising means for forming a loop in said strip, means for feeding strip to said loop at variable speeds, means for feeding the strip from said loop, means responsive to the position of said loop for varying the speed of its feeding means, means for stopping the feeding of the strip to the loop, and means responsive to said last named means for slowing down the means for feeding strip from said looP- I MAURICE D. AYERS.

REFERENCES CITED The following references are of record in the 

